If highmem and 2GB or more of memory are valid,
"this_frag-> page.p" indicates the highmem area,
so the result of page_address() is NULL and panic occurs.

This commit fixes this by using the skb_frag_dma_map() helper,
which takes care of mapping the skb fragment properly. Additionally,
the type of mapping is now tracked, so it can be unmapped using
dma_unmap_page or dma_unmap_single when appropriate.

Signed-off-by: Yuusuke Ashiduka <ashid...@jp.fujitsu.com>
---

Changes for v2:
 - Added signed-off
---
 drivers/net/ethernet/freescale/fec.h      |  1 +
 drivers/net/ethernet/freescale/fec_main.c | 48 +++++++++++++++++++++++--------
 2 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec.h 
b/drivers/net/ethernet/freescale/fec.h
index 5ea740b4cf14..5b187e8aacf0 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -463,6 +463,7 @@ struct bufdesc_prop {
 struct fec_enet_priv_tx_q {
        struct bufdesc_prop bd;
        unsigned char *tx_bounce[TX_RING_SIZE];
+       int tx_page_mapping[TX_RING_SIZE];
        struct  sk_buff *tx_skbuff[TX_RING_SIZE];
 
        unsigned short tx_stop_threshold;
diff --git a/drivers/net/ethernet/freescale/fec_main.c 
b/drivers/net/ethernet/freescale/fec_main.c
index 38160c2bebcb..b1562107e337 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -60,6 +60,7 @@
 #include <linux/if_vlan.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/prefetch.h>
+#include <linux/highmem.h>
 #include <soc/imx/cpuidle.h>
 
 #include <asm/cacheflush.h>
@@ -377,20 +378,28 @@ fec_enet_txq_submit_frag_skb(struct fec_enet_priv_tx_q 
*txq,
                        ebdp->cbd_esc = cpu_to_fec32(estatus);
                }
 
-               bufaddr = page_address(this_frag->page.p) + 
this_frag->page_offset;
-
                index = fec_enet_get_bd_index(bdp, &txq->bd);
-               if (((unsigned long) bufaddr) & fep->tx_align ||
+               txq->tx_page_mapping[index] = 0;
+               if (this_frag->page_offset & fep->tx_align ||
                        fep->quirks & FEC_QUIRK_SWAP_FRAME) {
+                       bufaddr = kmap_atomic(this_frag->page.p) +
+                                               this_frag->page_offset;
                        memcpy(txq->tx_bounce[index], bufaddr, frag_len);
+                       kunmap_atomic(bufaddr);
                        bufaddr = txq->tx_bounce[index];
 
                        if (fep->quirks & FEC_QUIRK_SWAP_FRAME)
                                swap_buffer(bufaddr, frag_len);
+                       addr = dma_map_single(&fep->pdev->dev,
+                                             bufaddr,
+                                             frag_len,
+                                             DMA_TO_DEVICE);
+               } else {
+                       txq->tx_page_mapping[index] = 1;
+                       addr = skb_frag_dma_map(&fep->pdev->dev, this_frag, 0,
+                                               frag_len, DMA_TO_DEVICE);
                }
 
-               addr = dma_map_single(&fep->pdev->dev, bufaddr, frag_len,
-                                     DMA_TO_DEVICE);
                if (dma_mapping_error(&fep->pdev->dev, addr)) {
                        if (net_ratelimit())
                                netdev_err(ndev, "Tx DMA memory map failed\n");
@@ -411,8 +420,16 @@ fec_enet_txq_submit_frag_skb(struct fec_enet_priv_tx_q 
*txq,
        bdp = txq->bd.cur;
        for (i = 0; i < frag; i++) {
                bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
-               dma_unmap_single(&fep->pdev->dev, 
fec32_to_cpu(bdp->cbd_bufaddr),
-                                fec16_to_cpu(bdp->cbd_datlen), DMA_TO_DEVICE);
+               if (txq->tx_page_mapping[index])
+                       dma_unmap_page(&fep->pdev->dev,
+                                      fec32_to_cpu(bdp->cbd_bufaddr),
+                                      fec16_to_cpu(bdp->cbd_datlen),
+                                      DMA_TO_DEVICE);
+               else
+                       dma_unmap_single(&fep->pdev->dev,
+                                        fec32_to_cpu(bdp->cbd_bufaddr),
+                                        fec16_to_cpu(bdp->cbd_datlen),
+                                        DMA_TO_DEVICE);
        }
        return ERR_PTR(-ENOMEM);
 }
@@ -1201,11 +1218,18 @@ fec_enet_tx_queue(struct net_device *ndev, u16 queue_id)
 
                skb = txq->tx_skbuff[index];
                txq->tx_skbuff[index] = NULL;
-               if (!IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr)))
-                       dma_unmap_single(&fep->pdev->dev,
-                                        fec32_to_cpu(bdp->cbd_bufaddr),
-                                        fec16_to_cpu(bdp->cbd_datlen),
-                                        DMA_TO_DEVICE);
+               if (!IS_TSO_HEADER(txq, fec32_to_cpu(bdp->cbd_bufaddr))) {
+                       if (txq->tx_page_mapping[index])
+                               dma_unmap_page(&fep->pdev->dev,
+                                              fec32_to_cpu(bdp->cbd_bufaddr),
+                                              fec16_to_cpu(bdp->cbd_datlen),
+                                              DMA_TO_DEVICE);
+                       else
+                               dma_unmap_single(&fep->pdev->dev,
+                                                fec32_to_cpu(bdp->cbd_bufaddr),
+                                                fec16_to_cpu(bdp->cbd_datlen),
+                                                DMA_TO_DEVICE);
+               }
                bdp->cbd_bufaddr = cpu_to_fec32(0);
                if (!skb)
                        goto skb_done;
-- 
2.11.0

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